The present invention relates to techniques pertaining to stream data recording and playing devices that can record and play stream data for, for example, broadcasted programs, and more particularly to stream data recording and playing devices, stream data recording and playing controlling devices, and stream data recording and playing methods that can record and play long time, continuous stream data.
MPEG-2 transport stream format (hereafter referred to as MPEG-2TS) has been used for stream data for, for example, programs broadcasted from broadcast stations. (“MPEG” is an abbreviation of Motion Picture Expert Group. MPEG-2 is a standard specified by ISO/IEC and is documented in ISO/IEC 13818.) Stream data in such a format as described above are sent out from a broadcast station at a predetermined transmission rate, and the system time clock of the receiving side decoder is synchronized with that of the sending side encoder in order to produce images and sound at proper timing.
If the received stream data are recorded in a recording and playing device (a recording medium), such as a hard disk, as they are and thereafter the data are played back, it is difficult to present the images or sound as they are received from a broadcast station. This is due to the fact that in general, the speed of data recording into or reading from a hard disk or the like is not specifically controlled (i.e., accurate speed is not guaranteed), and therefore, stream data with proper timing cannot be obtained if the data that have been read out are output without any processing.
In view of this problem, a time stamp recording system is known in which, when received data are recorded, time stamps are attached to the received data in the units of packets or the like based on the system time clock that is synchronized with the sender side encoder or the like. With this system, when playing back the recorded data, data read out from a recording medium are output at timing corresponding to time stamps, and as a result, images and sound can be presented just like the data received from a broadcast station.
However, with the above-described conventional stream data recording and playing device, although stream data can be recorded with the use of time stamp recording system as described above, it is necessary that time stamps attached to a series of stream data have continuity and therefore such a series of stream data must be recorded in a single recording and playing device. For this reason, the conventional device has a drawback in that it is difficult to record and/or play stream data having an amount of data larger than (longer than) the storage capacity of a single recording and playing device. It should be noted that when data to be recorded do not require synchronization of data transmission, they can be handled in a similar way to character data and still image data even though the data are image data or the like, so there will be no problem if the data are divided and stored into a plurality of recording media, as disclosed in Japanese Unexamined Patent Publication No. 2000-349833. In contrast, when the data are stream data, it is difficult to divide and record them while their continuity is being maintained.